Hydrocarbon conversion catalyst

ABSTRACT

A hydrocarbon conversion catalyst useful for hydrocracking hydrocarbons to more valuable products comprises one or more hydrogenation components supported on a base containing (1) a crystalline aluminosilicate zeolite having activity for cracking hydrocarbons and (2) a dispersion of silica-alumina in an alumina matrix.

BACKGROUND OF THE INVENTION

This invention relates to a hydrocracking process and a catalyst for usetherein. More particularly, it relates to a hydrocracking catalyst ofimproved activity, selectivity, and stability for producing middledistillates from heavy gas oils and the like under hydrocrackingconditions.

Petroleum refiners often produce desirable products such as turbinefuel, diesel fuel, and other middle distillate products by hydrocrackinga heavy gas oil, i.e., a hydrocarbon fraction having a boiling pointrange between about 700° F. and 1050° F. Hydrocracking is accomplishedby contacting the heavy gas oil at an elevated temperature and pressurein the presence of hydrogen and a suitable hydrocracking catalyst so asto yield a middle distillate fraction boiling in the 300°-700° F. rangeand containing the desired turbine and diesel fuels.

The three main catalytic properties by which the performance of ahydrocracking catalyst for producing middle distillate products isevaluated are activity, selectivity, and stability. Activity may bedetermined by comparing the temperature at which various catalysts mustbe utilized under otherwise constant hydrocracking conditions with thesame feedstock so as to produce a given percentage (usually 60%) ofproducts boiling below 700° F. The lower the activity temperature for agiven catalyst, the more active such a catalyst is in relation to acatalyst of higher activity temperature. Selectivity of hydrocrackingcatalysts may be determined during the foregoing described activity testand is measured as that percentage fraction of the 700° F.-minus productboiling in the range of middle distillate or midbarrel products, i.e.,300°-700° F. Stability is a measure of how well a catalyst maintains itsactivity over an extended time period when treating a given hydrocarbonfeedstock under the conditions of the activity test. Stability isgenerally measured in terms of the change in temperature required perday to maintain a 60% or other given conversion.

As could be expected, the aim of the art is to provide a catalyst havingat once the highest possible activity, selectivity, and stability.Catalysts usually utilized for hydrocracking comprise a Group VIII metalcomponent, most often cobalt or nickel sulfides, in combination with aGroup VIB metal component, most often molybdenum or tungsten sulfides,supported on a refractory oxide. For given proportions of Group VIII andGroup VIB metal components, the activity, selectivity, and stability ofa catalyst change dramatically with different supports. Supportmaterials comprising crystalline aluminosilicate zeolites, such asZeolite Y in the hydrogen form, generally provide high activity but lowselectivity, whereas support materials consisting essentially ofrefractory oxides, such as alumina, magnesia, and silica-alumina,generally have relatively poor activity but high selectivity.

The object of the present invention, therefore, is to provide ahydrocracking catalyst having superior overall catalytic properties forhydrocracking hydrocarbons. More specifically, it is an object of theinvention to provide a catalyst having superior overall activity,selectivity, and stability for hydrocracking in comparison to prior artcatalysts. It is a further object to provide a hydrocracking process forconverting gas oils and the like to middle distillate products. It is afurther object to provide a support or carrier material useful with ahydrogenation component as a catalyst for hydrogenating and/orhydrocracking hydrocarbons. These and other objects and advantages willbecome more apparent in light of the following description of theinvention.

SUMMARY OF THE INVENTION

The present invention is an improvement of the catalyst described inU.S. Pat. No. 4,097,365, herein incorporated by reference. The catalystdescribed in this reference is a midbarrel hydrocracking catalystcomprising hydrogenation components on a refractory oxide supportcomprising silica-alumina dispersed in a matrix of alumina. The presentinvention improves this catalyst by including in the support acrystalline aluminosilicate zeolite having cracking activity, such ashydrogen Y zeolite or a rare earth-exchange Y zeolite. In addition tohaving excellent activity for hydrodenitrogenation andhydrodesulfurization, the catalyst of the invention has been found tohave superior overall properties of activity, selectivity, and stabilityfor hydrocracking in comparison to the catalyst described in U.S. Pat.No. 4,097,365. In the usual instance, the catalyst of the invention ismore active, more stable, and more selective than comparison catalystshaving supports consisting essentially of either a dispersion ofsilica-alumina in an alumina matrix or a zeolite plus a refractory oxideother than a dispersion of silica-alumina in an alumina matrix.

In its broadest embodiment, the present invention provides a catalystsupport comprising in intimate admixture (1) a crystallinealuminosilicate zeolite having cracking activity and (2) a dispersion ofsilica-alumina in an alumina matrix. Although the support is mostpreferred when used in conjunction with a hydrogenation component, itmay itself be utilized in the absence of a hydrogenation component as acatalyst for converting hydrocarbons to more valuable products by acidcatalyzed reactions, such as catalytic cracking, isomerization ofn-paraffins to isoparaffins, isomerization of alkyl aromatics,alkylation, and transalkylation of alkyl aromatics.

DETAILED DESCRIPTION OF THE INVENTION

The catalyst of the invention is an intimate composite of one or morehydrogenation components, a crystalline aluminosilicate zeolite havingcatalytic activity for cracking hydrocarbons, and a dispersion ofsilica-alumina in a matrix consisting essentially of alumina. Thehydrogenation components useful in the invention are the metals, oxides,and sulfides of uranium, the Group VIII elements, and the Group VIBelements. The most suitable hydrogenation components are selected fromthe group consisting of the metals, oxides, and sulfides of platinum,palladium, cobalt, nickel, tuungsten, and molybdenum. The preferredcatalyst contains at least one Group VIII metal component, and at leastone Group VIB metal component, with the most preferred combination beinga nickel and/or cobalt component with a molybdenum and/or tungstencomponent.

The hydrogenation component or components are intimately composited on abase or support comprising a mixture of one or more crystallinealuminosilicate zeolites having cracking activity and a heterogeneousdispersion of finely divided silica-alumina in a matrix of alumina. Thesuitable zeolites for use herein include crystalline aluminosilicatemolecular sieves having catalytic activity for cracking hydrocarbons.Many naturally-occurring and synthetic crystalline aluminosilicatezeolites known in the art are useful in the invention, including, forexample, faujasite, mordenite, erionite, Zeolite Y, Zeolite X, ZeoliteL, Zeolite Omega, Zeolite ZSM-4, and their modifications. These andother such zeolitic molecular sieves are known to have activity forcracking hydrocarbons when a substantial proportion of the ion exchangesites are occupied with hydrogen ions or multivalent metal-containingcations, particularly rare earth cations. Normally, crystallinealuminosilicate zeolites are obtained in the alkali metal form and assuch are largely inactive for catalytically cracking hydrocarbons. Toproduce a zeolite having cracking activity, the alkali metals areusually replaced with multivalent metal-containing cations, hydrogenions, or hydrogen ion precursors (e.g. ammonium ion). This replacementof cations is generally accomplished by ion exchange, a methodwell-known in the art wherein the zeolite in the sodium or other alkalimetal form is contacted with an aqueous solution containing hydrogenions, ammonium ions, rare earth ions, or other suitable cations.Replacing even a portion of the sodium ions produces a zeolite havingsome cracking activity, but reducing the alkali metal content to lessthan 5 wt.%, preferably to less than 1 wt.%, and most preferably to lessthan about 0.5 wt.% (calculated as the alkali metal oxides), results ina material having substantial cracking activity, with the activityvarying according to the zeolite and the amount of alkali metalsremoved.

In addition to the zeolites referred to above, many other crystallinealuminosilicate zeolites in their non-alkali metal forms may be utilizedin the catalyst support of the invention. Preferred zeolites contain atleast 50% of their pore volume in pores of diameter greater than 8Angstroms, with Zeolite Y (and its modifications) in the hydrogen formor in other forms imparting cracking activity to the zeolite beingpreferred zeolites for use in the invention. Also preferred are zeolitesthat have been ion-exchanged with ammonium ions and then steamstabilized in accordance with the teachings of U.S. Pat. No. 3,929,672,herein incorporated by reference. The most highly preferred zeolite is amaterial known as LZ-10, a zeolitic molecular sieve available from UnionCarbide, Linde Division. Although LZ-10 is a proprietary material, it isknown that LZ-10 is a modified Y zeolite having a silica to aluminaratio between about 3.5 and 4.0, a surface area between about 500 and700 m² /gm, a unit cell size between about 24.25 and 24.35 Angstroms,water absorption capacity less than about 8% by weight of the zeolite(at 4.6 mm partial pressure of water vapor and 25° C.), and anion-exchange capacity less than 20% of that of a sodium Y zeolite ofcomparable silica to alumina ratio. When used as a hydrocrackingcatalyst, LZ-10 is highly active and selective for midbarrelhydrocracking, especially when composited with alumina and suitablehydrogenation components.

The support material utilized in the invention usually comprises between2 and about 80% by weight, preferably between about 10 and about 70% byweight, of a crystalline aluminosilicate zeolite such as LZ-10. Thesupport also comprises a substantial proportion of a heterogeneousdispersion of finely divided silica-alumina in an alumina matrix.Usually, the dispersion comprises at least 15% by weight of the support,with the preferred and most preferred proportions being in therespective ranges of 30 to 98% and 30 to 90% by weight of the support.

One convenient method of preparing the catalyst support herein is tocomull an alumina hydrogel with a silica-alumina cogel in hydrous or dryform. The cogel is preferably homogeneous and may be prepared in amanner such as that described in U.S. Pat. No. 3,210,294. Alternatively,the alumina hydrogel may by comulled with a "graft copolymer" of silicaand alumina that has been prepared, for example, by first impregnating asilica hydrogel with an alumina salt and then precipitating alumina gelin the pores of the silica hydrogel by contact with ammonium hydroxide.In the usual case, the cogel or copolymer (either of which usuallycomprses silica in a proportion by dry weight of 20 to 96%, preferably50 to 90%) is mulled with the alumina hydrogel such that the cogel orcopolymer comprises 5 to 75% by weight, preferably 20 to 65% by weight,of the mixture. The overall silica content of the resulting dispersionon a dry basis is usually between 1 and 75 wt.%, preferably between 5and 45 wt.%.

The mulled mixture of alumina gel with either a silica-alumina cogel ora silica and alumina "graft copolymer" may be utilized in the gel formor may be dried and/or calcined prior to combination with the zeolite.In the preferred method of preparation, the cogel or copolymer is spraydried and then crushed to a powdered form, following which the powder ismulled with a zeolite powder containing hydrogen ions, hydrogen ionprecursors, or multivalent metal-containing cations, the amounts ofcogel or copolymer mulled with said zeolite being such that the supportwill ultimately contain zeolite and dispersion in the proportions setforth hereinbefore. If desired, a binder may also be incorporated intothe mulling mixture, as also may one or more active metal hydrogenationcomponents in forms such as ammonium heptamolybdate, nickel nitrate orchloride, ammonium metatungstate, cobalt nitrate or chloride, etc. Aftermulling, the mixture is extruded through a die having suitable openingstherein, such as circular openings of diameters between about 1/32 and1/8 inch. Preferably, however, the die has openings therein in the shapeof three-leaf clovers so as to produce an extrudate material similar tothat shown in FIGS. 8 and 8A of U.S. Pat. No. 4,028,227. The extrudedmaterial is cut into lengths of about 1/32 to 3/4 inch, preferably 1/4to 1/2 inch, dried, and calcined at an elevated temperature.

If desired, hydrogenation components may be composited with the supportby impregnation; tht is, rather than comulling the hydrogenationcomponents with the support materials, the zeolite and dispersion aremulled, extruded, cut into appropriate lengths, and calcined. Theresulting particles are then contacted with one or more solutionscontaining the desired hydrogenation components in dissolved form, andthe composite particles thus prepared are dried and calcined to producefinished catalyst particles.

Usually, the finished catalyst contains at least about 0.5 wt.% ofhydrogenation components, calculated as the metals. In the usualinstance, wherein a Group VIII metal and a Group VIB metal component areutilized in combination, the finished catalyst contains between about 5%and 35%, preferably between about 10 and 30% by weight, calculated asthe respective trioxides, of the Group VIB metal components and betweenabout 2% and 15%, preferably between 3 and 10% by weight, calculated asthe respective monoxides, of the Group VIII metal components.

If desired, a phosphorous component may also be incorporated in thecatalyst by either comulling the support materials with phosphoric acidor including phosphoric acid in the impregnating solution. Usual andpreferred proportions of phosphorus in the catalyst fall in the rangesof 1 to 10 wt.% and 3 to 8 wt.%, calculated as P₂ O₅.

The hydrogenation components, which will largely be present in theiroxide forms after calcination in air, may be converted to their sulfideforms, if desired, by contact at elevated temperatures with a reducingatmosphere comprising hydrogen sulfide. More conveniently, the catalystis sulfided in situ, i.e., by contact with a sulfur-containing feedstockto be catalytically converted to more valuable hydrocarbons in suchprocesses as hydrocracking, hydrotreating, etc.

The foregoing described catalysts are especially useful forhydrogenation reactions, such as hydrodenitrogenating andhydrodesulfurizing hydrocarbons, but are particularly useful withrespect to hydrocracking to convert a hydrocarbon feedstock to a morevaluable product of lower average boiling point and lower averagemolecular weight. The feedstocks that may be treated herein byhydrogenation include all mineral oils and synthetic oils (e.g., shaleoil, tar sand products, etc.) and fractions thereof. Typical feedstocksinclude straight run gas oils, vacuum gas oils, deasphalted vacuum andatomspheric residua, coker distillates, and catcracker distillates,Preferred hydrocracking feedstocks include gas oils and otherhydrocarbon fractions having at least 50% by weight of their componentsboiling above 700° F. Suitable and preferred conditions forhydrocracking gas oil feedstocks, as well as for hydrodenitrogenatingand/or hydrodesulfurizing such feedstocks, are:

                  TABLE I                                                         ______________________________________                                                       Suitable                                                                             Preferred                                               ______________________________________                                        Temperature, °F.                                                                        500-850   600-800                                            Pressure, psig   750-3500 1000-3000                                           LHSV             0.3-5.0  0.5-3.0                                             H.sub.2 /Oil, MSCF/bbl                                                                         1-10     2-8                                                 ______________________________________                                    

As will be shown by the following Examples, which are provided forillustrative purposes and are not to be construed as limiting the scopeof the invention as defined by the claims, the present catalysts havebeen found to possess superior overall catalytic properties with respectto activity, selectivity, and stability when conversion of gas oils tomidbarrel products by hydrocracking is desired. In many instances, thecatalysts of the invention have been found to be superior in each of thethree main performance categories of activity, selectivity, andstability.

EXAMPLE I

An experiment was performed to compare the activity, selectivity, andstability of catalysts of the invention containing LZ-10 and adispersion of silica alumina in a gamma alumina matrix versus catalystshaving supports consisting essentially of LZ-10 and gamma alumina.Following are the preparation procedures used for Catalyst Nos. 1through 4, with Catalyst Nos. 2 and 3 being representative of theinvention and Catalyst Nos. 1 and 4 being the comparison catalysts.

CATALYST NO. 1

A mixture of 10% by weight powdered LZ-10 that had been ion-exchangedwith ammonium nitrate to reduce the sodium content to about 0.1% byweight sodium (as Na₂ O) and 90% by weight gamma alumina was extrudedthrough a die having openings therein in a three-leaf clover shape, eachleaf being defined by about a 270° arc of a circle having a diameterbetween about 0.02 and 0.04 inches. The extruded material was cut into1/4-1/2 inch lengths and calcined at 900° F. in air to convert the LZ-10material to the hydrogen form. The calcined particles (300 gm) were thenimpregnated with 330 ml of an aqueous solution containing 67 gm ofnickel nitrate (Ni(NO₃)₂.6H₂ O) and 108 gm of ammonium metatungstate(91% WO₃ by weight). After removing excess liquid, the catalyst wasdried at 230° F. and calcined at 900° F. in flowing air. The finalcatalyst contained 4.4 wt.% nickel components (calculated as NiO) and25.0 wt.% tungsten components (calculated as WO₃).

CATALYST NO. 2

The procedure described for Catalyst No. 1 was repeated except that inplace of alumina a dispersion of spray dried, powdered silica-alumina inalumina prepared in a manner similar to that of Example 3 of U.S. Pat.No. 4,097,365 was used. The dispersion was prepared by mixing 44 partsby dry weight of a 75/25 silica-alumina graft copolymer and 56 parts byweight of hydrous alumina gel. In the final catalyst, the supportconsisted essentially of 10% LZ-10 in the hydrogen form and 90%dispersion of silica alumina in an alumina matrix, the dispersionconsisting overall of 33% by weight silica and 67% by weight alumina.The resulting catalyst contained 4.1% by weight nickel components (asNiO) and 24.2% by weight tungsten components (as WO₃).

CATALYST NO. 3

This catalyst was prepared in the same manner as Catalyst No. 2 exceptthat the proportions of LZ-10 and dispersion admixed to prepare thesupport were adjusted so that in the final catalyst the proportion ofLZ-10 in the support was 5% by weight and that of the dispersion, 95% byweight. The final catalyst contained 4.1% by weight nickel components(as NiO) and 23.6% by weight tungsten components (as WO₃) on a supportof 5% LZ-10 and 95% dispersion.

CATALYST NO. 4

This catalyst was prepared in the same manner as Catalyst No. 1 exceptthat the proportions of LZ-10 and alumina admixed during preparationwere such that in the final catalyst the proportion of LZ-10 in thesupport was 20% by weight and that of the gamma alumina, 80% by weight.The final catalyst contained 4.1% by weight nickel components (as NiO)and 24.4% by weight tungsten components (as WO₃) on a support of 20%LZ-10 and 80% gamma alumina.

Each of the foregoing catalysts was then activity tested according tothe following method. A preheated light Arabian vacuum gas oil havingthe chemical and physical properties shown in Table II was passed on aonce-through basis through an isothermal reactor containing 140 ml ofcatalyst particles uniformly mixed with 160 ml of 10 to 20 mesh quartz.Operating conditions were as follows: 1.0 LHSV, 2000 psig, aonce-through hydrogen flow of 10,000 scf/bbl, and a run length ofapproximately 10 days. The temperature of the reactor was adjusted toprovide a 60 volume percent conversion to products boiling at 700° F. orless. The results of the activity testing are reported in Table III.

                  TABLE II                                                        ______________________________________                                        PROPERTIES OF LIGHT ARABIAN VACUUM GAS OIL                                    ______________________________________                                        Gravity, °API                                                                    22.3    Pour Point, °F.                                                                           100.0                                    Distillation, °F., D-1160                                                            Sulfur, XRF, wt. % 2.37                                         IBP/5   693/760   Nitrogen, KJEL, wt. %                                                                            0.079                                                      Hydrogen, wt. %    12.20                                    10/20   777/799   Chlorine, ppm      <1.0                                     30/40   815/832   Carbon Residue, D-189, wt. %                                                                     0.14                                     50/60   850/870   Viscosity, SSU at 100° F.                                                                 319.0                                    70/80   894/920   Viscosity, SSU at 210° F.                                                                 51.1                                                       Specific Gravity   0.9200                                   90/95   958/979                                                               EP/% Rec.                                                                             1053/99.0                                                             ______________________________________                                    

                  TABLE III                                                       ______________________________________                                                           Activity.sup.1                                                                          Selectivity.sup.2                                                   Reactor   Vol. %                                                Catalyst      Temp. to  Conv. to                                              Description   Provide   300°-700° F.                                                             Stability.sup.3                         No.  of Support    60% Conv. Product  °F./day                          ______________________________________                                        1    10% LZ-10 and 772° F.                                                                          83.5     0.68                                         90% Gamma                                                                     Alumina                                                                  2    10% LZ-10 and 750° F.                                                                          83.5     -0.72                                        90% SiO.sub.2 --Al.sub.2 O.sub.3 in                                           Gamma Alumina                                                                 Matrix                                                                   3    5% LZ-10 and  776° F.                                                                          87.4     0.09                                         95% SiO.sub.2 --Al.sub.2 O.sub.3 in                                           Gamma Alumina                                                                 Matrix                                                                   4    20% LZ-10 and 750° F.                                                                          75.2     0.39                                         80% Gamma                                                                     Alumina                                                                  ______________________________________                                         .sup.1 Activity data are those obtained on tenth day of run.                  .sup.2 Selectivity data are an average of data obtained over 10 days and      are calculated as the volume of 300°-700° F. components to      the total volume of components boiling at or below 700° F.             .sup.3 Stability data were calculated using the reactor temperature           required to produce a 60% conversion on the 2nd and 10th days of the run.

The data in Table III reveal that in comparison to the two hydrocrackingcatalysts having supports consisting of LZ-10 and gamma alumina, thecatalysts of the invention are far superior in terms of overallactivity, selectivity, and stability. A comparison of Catalyst Nos. 1and 2 shows that, for the same percentage of LZ-10 in the support,Catalyst No. 2 prepared in accordance with the invention was 22° F. moreactive and much more stable than Catalyst No. 1. In addition, CatalystNo. 2 proved to be as selective for producing midbarrel products asCatalyst No. 1. Comparing Catalysts Nos. 2 and 4 and Catalysts 3 and 1shows that the catalysts of the invention are as active, butsubstantially more stable and selective, than their LZ-10-aluminacomparisons containing twice as much zeolite.

EXAMPLE II

A second experiment was performed under the run conditions of Example Ito demonstrate the improved performance attainable with the catalyst ofthe invention in comparison to the catalysts described in U.S. Pat. No.4,097,365. The catalyst utilized in the experiment were prepared asfollows:

CATALYST NO. 5

A catalyst support was prepared in the same manner as described inExample 3 of U.S. Pat. No. 4,097,365 except that 54 parts of thesilica-alumina graft copolymer were mixed with 46 parts of the hydrousalumina gel. The support (in the size and shape as Catalyst No. 1) wascalcined and impregnated with a nickel nitrate-ammonium metatungstatesolution as in the preparation of Catalyst No. 1, and then dried andcalcined in the same way. The final catalyst contained 4.1 wt.% nickelcomponents (as NiO) and 24.4 wt.% tungsten components (as WO₃) supportedon a base consisting essentially of a dispersion of 75/25 silica-aluminain an alumina matrix, the base having an overall silica content of 40%and an overall alumina content of 60%.

CATALYST NO. 6

This catalyst was prepared in the same manner as Catalyst No. 5 exceptthat LZ-10 in the ammonium form and peptized alumina binder wereincorporated into the support such that, after calcination, LZ-10 in thehydrogen form comprised 10 percent by weight of the support and thebinder comprised 20 percent by weight of the support.

The results obtained from testing Catalysts Nos. 5 and 6 for activity,selectivity, and stability are reported in Table IV.

                  TABLE IV                                                        ______________________________________                                                           Activity.sup.1                                                                          Selectivity.sup.2                                                   Reactor   Vol. %                                                Catalyst      Temp. to  Conv. to                                              Description   Provide   300°-700° F.                                                             Stability.sup.3                         No.  of Support    60% Conv. Product  °F./day                          ______________________________________                                        5    Dispersion of 773° F.                                                                          88.7     0.23                                         SiO.sub.2 /Al.sub.2 O.sub.3 in                                                Gamma Alumina                                                                 Matrix                                                                   6    10% LZ-10 and 753° F.                                                                          87.4     0.05                                         90% Dispersion                                                                of SiO.sub.2 --Al.sub.2 O.sub.3 in                                            Gamma Alumina                                                            ______________________________________                                         .sup.1 Activity data are those obtained on tenth day of run.                  .sup.2 Selectivity data are an average of data obtained over 10 days and      are calculated as the volume of 300°-700° F. components to      the total volume of components boiling at or below 700° F.             .sup.3 Stability data were calculated using the reactor temperatures          required to produce a 60% conversion on the 2nd and 10th days of the run.

As is self-evident from the data in Table IV, the catalyst of theinvention, Catalyst No. 6, proved far superior to a catalyst similar tothat described in Example 3 of U.S. Pat. No. 4,097,365. Catalyst No. 6provides substantially more activity and stability than Catalyst No. 5with no significant loss in selectivity.

EXAMPLE III

A third comparison experiment was run to determine the activity of twocatalysts of the invention comprising nickel and molybdenum componentson supports comprising LZ-10 and a dispersion of silica-alumina in agamma alumina matrix versus a catalyst comprising nickel and molybdenumcomponents on a support comprising LZ-10 and alumina but containing nodispersion. The catalysts were prepared as follows:

CATALYST NO. 7

Sixty grams of gamma alumina powder were comulled with 120 gm LZ-10 inthe ammonia form, 20 gm peptized alumina, 75 gm ammonium heptamolybdate((NH₄)₆ Mo₇ O₂₄.4H₂ O), and 85 gm nickel nitrate hexahydrate. The mulledmixture was extruded through a die similar to that used in preparingCatalyst No. 1, cut into 1/4-1/2 inch lengths, and calcined in air at900° F. The resulting catalyst contained 7.7 wt.% nickel components (asNiO), 21.9 wt.% molybdenum components (as MoO₃), about 43 wt.% LZ-10,about 21 wt.% gamma alumina, and the remainder (about 7 wt.%) peptizedalumina.

CATALYST NO. 8

This catalyst was prepared in the same fashion as was Catalyst No. 7except that, in place of the gamma alumina, 60 gm of a powdereddispersion of 75/25 silica-alumina in a gamma alumina matrix was used.The dispersion was prepared by spray drying a mixture comprising 33parts by weight silica-alumina graft copolymer with 67 parts by weightof hydrous alumina gel. The final catalyst contained 7.4 wt.% nickelcomponents (as NiO), 21.5 wt.% molybdenum components (as MoO₃), about 43wt.% LZ-10, about 7% of peptized alumina, and about 21% of thedispersion containing 25 wt.% silica and 75 wt.% alumina overall.

CATALYST NO. 9

This catalyst was prepared in the same manner as Catalyst No. 8 exceptthat the dispersion was prepared by mixing 54 parts by weight of 75/25silica-alumina graft copolymer with 46 parts by weight of hydrousalumina gel. The final catalyst was of the same composition as CatalystNo. 8 except for the overall silica and alumina contents of thedispersion, which were 40% and 60% by weight, respectively.

The foregoing catalysts were subjected to the 10-day activity testsdescribed in Example I, and the results are shown in Table V. As shown,the results prove the superiority of the catalysts of the invention(i.e., Catalysts Nos. 8 and 9) in all categories. In addition, the datashow the improvement obtained when the silica contents of the catalystsof the invention are increased.

                  TABLE V                                                         ______________________________________                                                           Activity.sup.1                                                                          Selectivity.sup.2                                                   Reactor   Vol. %                                                Catalyst      Temp. To  Conv. to                                              Description   Provide   300°-700° F.                                                             Stability.sup.3                         No.  of Support    60% Conv. Product  °F./day                          ______________________________________                                        7    LZ-10 and     745° F.                                                                          74.8     1.43                                         Gamma Alumina                                                            8    LZ-10 and     743° F.                                                                          79.4     0.17                                         SiO.sub.2 --Al.sub.2 O.sub.3 in                                               Gamma Alumina                                                                 Matrix                                                                        (25% SiO.sub.2 Overall)                                                  9    LZ-10 and     733° F.                                                                          79.5     0.88                                         SiO.sub.2 --Al.sub.2 O.sub.3 in                                               Gamma Alumina                                                                 Matrix                                                                        (40% SiO.sub.2 O.sub.2 Overall)                                          ______________________________________                                         .sup.1 Activity data are those obtained on tenth day of run.                  .sup.2 Selectivity data are an average of data obtained over 10 days and      are calculated as the volume of 300°-700° F. components to      the total volume of components boiling at or below 700° F.             .sup.3 Stability data were calculated using the reactor temperatures          required to produce a 60% conversion on the 2nd and 10th days of the run.

EXAMPLE IV

A fourth experiment was conducted to compare the catalytic properties ofa catalyst of the invention incorporating a stabilized Y zeolite withthe catalytic properties of a similar catalyst containing stabilized Yzeolite but containing no dispersion of silica-alumina in an aluminamatrix. The two catalysts were prepared as follows:

CATALYST NO. 10

A mixture of 40 gm stabilized Y zeolite (prepared in accordance with themethod described in U.S. Pat. No. 3,929,672 for Catalyst A in Example 16but without adding palladium), 40 gm peptized alumina binder, and 120 gmof dispersion of the kind described for Catalyst No. 9 were comulledwith a 380 ml aqueous solution containing 78 gm ammonium heptamolybdatetetrahydrate, 29.1 gm phosphoric acid (85% H₃ PO₄), and 85 gm nickelnitrate hexahydrate. The resulting material was extruded in the samemanner as Catalyst No. 1, cut into particles of 1/4-1/2 inch length, andcalcined in air at 900° F. The final catalyst contained about 6 wt.%nickel components (as NiO), about 19 wt.% molybdenum components (asMoO₃), and about 6 wt.% phosphorus components (as P₂ O₅).

CATALYST NO. 11

This catalyst was prepared in a manner similar to that of Catalyst No.10 with the major difference being (1) that the comulled mixture wasextruded through a die having circular openings therein of about 1/16inch diameter and (2) the comulled mixture contained 120 gm of powderedgamma alumina instead of the dispersion. The resulting catalyst had thesame percentage composition of nickel, molybdenum, and phosphoruscomponents as Catalyst No. 10.

The foregoing catalysts were then tested in a manner similar to thatdescribed in Example I except that Catalyst No. 10 was run for 13.6 daysand Catalyst No. 11 for 8 days. The data obtained are presented in TableVI.

                  TABLE VI                                                        ______________________________________                                                          Activity.sup.1                                                                          Selectivity.sup.2                                                   Reactor   Vol. %                                                 Catalyst     Temp. To  Conv. To                                               Description  Provide   300°-700° F.                                                             Stability.sup.3                          No.  of Support   60% Conv. Product  °F./Day                           ______________________________________                                        10   Stabilized Y plus                                                                          773° F.                                                                          70.0     1.1 (days                                     SiO.sub.2 --Al.sub.2 O.sub.3 in 3.2 to 10)                                    Gamma Alumina                   0 (days 10.9                                  Matrix                          to 13.6)                                 11   Stabilized Y plus                                                                          739° F.                                                                          73.0     0.58 (days                                    Gamma Alumina                   2.8 to 8.1)                              ______________________________________                                         .sup.1 Activity as reported for Catalyst No. 10 is a corrected value          obtained from data determined for the 10th day of the run, and the            activity data reported for Catalyst No. 11 is extrapolated from data          derived on the eighth day of the run.                                         .sup.2 Selectivity data are the average of data obtained during first 10      days with Catalyst No. 10 and the 8 days of run with Catalyst No. 11.         .sup.3 Stability data were calculated using the reactor temperatures          required to produce a 60% conversion on the days specified in the Table. 

The results in Table VI again show the overall superiority of thecatalyst of the invention (Catalyst No. 10) with respect to activity,selectivity, and stability. The 6° F. differential in activity betweenthe catalyst of the invention and the comparison catalyst representsabout a 20% improvement in activity. Especially significant is the factthat after 10.9 days, Catalyst No. 10 showed no signs of deactivation,and thus the high activity indicated by the 733° F. result could beexpected to be maintained.

EXAMPLE V

Catalyst No. 12 was prepared in the same manner as Catalyst No. 9 exceptthat LZ-20 rather than LZ-10 was utilized. (LZ-20 is a crystallinealuminosilicate zeolite, available from Union Carbide, Linde Division,having a unit cell size, a water sorption capacity, a surface area, andan ion exchange capacity somewhat higher than that of LZ-10). Thecatalyst was tested in the same manner as described in Example I exceptthat the run length was 8.5 days rather than 10 days. The results of theexperiment were as follows: Activity: 733° F. (the operating temperatureon the last day of run), Selectivity: 67.0% (as the average percentageconversion to middle distillates during the run), and Stability: 1.94°F./day as calculated between 2.1 days and the end of run and 1.86°F./day between 5.3 days and end of the run. A comparison of these datawith those of Catalyst No. 9 in Example III indicate that better resultsare obtained with LZ-10 in the catalyst support of the invention thanwith LZ-20.

EXAMPLE VI

Catalyst No. 13 was prepared by mulling a mixture consisting essentiallyof 140 gm of a dispersion of silica-alumina in an alumina matrix as wasused to prepare Catalyst No. 5, 20 gm LZ-10 in ammonia form (i.e., as inExample I), and 40 gm peptized alumina with 380 ml of an aqueoussolution containing 78 gm ammonium heptamolybdate tetrahydrate, 29.1 gmphosphoric acid (85% H₃ PO₄), and 85 gm nickel nitrate hexahydrate. Themulled mixture was wet sufficiently to form a paste and extruded througha die similar to that described in Example I. The extrudate was cut into1/4-178 inch particles in length, dried, and calcined at 900° F. Thefinished catalyst contained 7.6 wt.% nickel components (as NiO), 21.2wt.% molybdenum components (as MoO₃), and 7.1 wt.% phosphorus components(as P₂ O₅).

The foregoing catalyst was tested for its catalytic properties in thesame manner as described in Example I, and the results were as follows:Activity: 750° F. on the tenth day of run, Selectivity: 85.6 as theaverage over the ten days of operation, and Stability: 0.85° F./day fromdays 2 through 10 and 0.11° F./day from days 5.8 through 10. Theseresults indicate the high activity, selectivity, and stability of thisembodiment of the catalyst of the invention.

EXAMPLE VII

During the runs performed on Catalyst No. 6 in Example II and CatalystNo. 10 in Example IV, samples of the product oils were obtained andanalyzed for sulfur content by X-ray fluorescence analysis and nitrogencontent by coulometric analysis. As shown by the data in Table II, thesulfur and nitrogen contents of the feedstock were 2.37 wt.% and 0.079wt.%, respectively. In Table VII are reported the results of theanalyses performed on the samples of product oil obtained in theexperiments described in Examples II and IV. The data in Table VIIindicate that Catalysts Nos. 6 and 10 had substantial activity forhydrodenitrogenation and hydrodesulfurization.

                  TABLE VII                                                       ______________________________________                                                       Days into   Sulfur in                                                 Temp.   Run When    Product,                                                                             Nitrogen in                                 Catalyst                                                                             °F.                                                                            Sample Taken                                                                              ppmw   Product, ppmw                               ______________________________________                                        No.  6 750     10          6      --                                          No. 10 730     10          93     2.2                                         No. 10 734     13          62     1.3                                         ______________________________________                                    

EXAMPLE VIII

Zeolite LZ-10 is believed to be prepared by high temperature, steamcalcining the hydrothermally stable and ammonia-stable Zeolite Ycompositions described in U.S. Pat. No. 3,929,672, herein incorporatedby reference. One specific method by which LZ-10 may be prepared is asfollows:

A sample of air-dried ammonium exchanged Zeolite Y having a compositionexclusive of water of hydration:

    0.156 Na.sub.2 O:0.849(NH.sub.4).sub.2 O:Al.sub.2 O.sub.3 :5.13 SiO.sub.2

is tableted into 1/2 inch diameter slugs and charged to a Vycor tubeprovided with external heating means and having a 24 inch length and a2.5 inch diameter. The temperature of the charge is first raised to 600°C. in about 25 minutes and then held at this temperature for one hour.During this 1.25 hour period, a pure steam atmosphere at 14.7 psiagenerated from demineralized water is passed upwardly through the chargeat a rate of 0.1 to 0.5 lbs/hr. Ammonia gas generated during the heatingdeammoniation of the zeolite is passed from the system continuously. Atthe termination of the heating period, the steam flow is stopped and thetemperature of the charge is lowered to ambient room temperature over aperiod of five minutes. The charge is removed from the Vycor tube, andthe sodium cation content of the steamed material is reduced to about0.25 weight percent (as Na₂ O) by ion exchange using an aqueous solutionof 30 weight percent ammonium chloride at reflux.

The low sodium material thus prepared is recharged to the Vycor tube andagain steamed, this time using pure steam at 14.7 psia and a temperatureof 800° C. for 4 hours. The product is then cooled to ambienttemperature and has the following typical characteristics: SurfaceArea=530 m² /gm, Adsorptive Capacity of water at 4.6 mm partial pressureand 25° C.=4.6 weight percent, and an ion exchange capacity equal to 4%of that of a sodium Y zeolite having a comparable SiO₂ :Al₂ O₃ ratio.(The comparable sodium Y zeolite to which LZ-10 zeolite is compared inthe specification and claims herein is a sodium Y zeolite havingessentially the same silica to alumina ratio as LZ-10 and having asodium to aluminum content such that the ratio of Na₂ O:Al₂ O₃ is equalto 1.0).

Although the invention has been described in conjunction with severalcomparative examples, may variations, modifications, and alternatives ofthe invention as described will be apparent to those skilled in the art.Accordingly, it is intended to embrace within the invention all suchvariations, modifications, and alternatives as fall within the spiritand scope of the appended claims.

I claim:
 1. A composition of matter useful as a catalyst base forsupporting active hydrogenation metal components or for catalyzing acidcatalyzed hydrocarbon conversion reactions comprising in intimateheterogeneous mixture (1) a modified hydrogen crystallinealuminosilicate Y zeolite having activity for catalytically crackinghydrocarbons and having a unit cell size between 24.25 and 24.35 Å and awater absorption capacity, at 4.6 mm water vapor partial pressure and25° C., less than 8% by weight of the zeolite and (2) a dispersion ofsilica-alumina in a gamma alumina matrix.
 2. A composition of matter asdefined in claim 1 wherein said dispersion of silica-alumina in a gammaalumina matrix comprises between about 50 and 90% by weight ofsilica-alumina containing 20 to 65% by weight silica.
 3. A compositionas defined in claim 1 or 2 wherein the alkali metal components contentof the crystalline aluminosilicate zeolite is less than 0.5% by weight,as calculated as the alkali metal oxides.
 4. A composition of matter asdefined in claim 3 wherein said zeolite has an ion exchange capacitywhen in the sodium form less than 20% of that of a sodium Y zeolite ofcomparable SiO₂ :Al₂ O₃ ratio.
 5. A composition of matter as defined inclaim 1 or 2 wherein said zeolite has an ion exchange capacity when inthe sodium form less than 20% of that of a sodium Y zeolite ofcomparable SiO₂ :Al₂ O₃ ratio.
 6. A catalyst composition comprising inintimate admixture at least one hydrogenation component, a crystallinealuminosilicate zeolite having catalytic activity for crackinghydrocarbons, and a dispersion of silica-alumina in a matrix consistingessentially of alumina.
 7. A catalyst composition comprising at leastone hydrogenation component selected from the group consisting of GroupVIII and Group VIB metals, their oxides, and sulfides on a supportcomprising an intimate admixture of (1) a crystalline aluminosilicatezeolite having catalytic activity for cracking hydrocarbons and (2)silica-alumina dispersed in a matrix consisting essentially of alumina.8. A composition as defined in claim 6 or 7 wherein said hydrogenationcomponent is selected from the group consisting of platinum, palladium,cobalt, nickel, tungsten, molybdenum, their oxides, and their sulfides.9. A composition as defined in claim 8 wherein said zeolite is Zeolite Yion exchanged to contain less than about 0.5% by weight alkali metalcomponents, calculated as the oxides thereof, said Zeolite Y containingcations selected from the group consisting of hydrogen ions and rareearth cations.
 10. A composition as defined in claim 8 wherein saidzeolite is a modified hydrogen Y zeolite having a SiO₂ :Al₂ O₃ ratiobetween about 3.5 and 6, a surface area between about 500 and 700 m²/gm, a unit cell size between about 24.25 and 24.35 Å, an ion exchangecapacity when in the sodium form less than 20% of that of a sodium Yzeolite of comparable SiO₂ :Al₂ O₃, and a water absorption capacity, at4.6 mm water vapor partial pressure and 25° C., less than 8% by weightof the zeolite.
 11. A hydrocracking catalyst composition comprising inintimate admixture at least one Group VIB metal component and at leastone Group VIII metal component, a crystalline aluminosilicate zeolitecontaining less than about 5% by weight of alkali metal components,calculated as the oxides thereof, and a dispersion of silica-alumina ina matrix consisting essentially of alumina.
 12. A hydrocracking catalystcomposition comprising a first metal component selected from the groupconsisting of nickel, nickel compounds, cobalt, cobalt compounds, andcombinations of the foregoing, and a second metal component selectedfrom the group consisting of molybdenum, molybdenum compounds, tungsten,tungsten compounds, and combinations of the foregoing, said first andsecond metal components being supported on an intimate admixturecomprising (1) a crystalline aluminosilicate zeolite having at least 50%of its pore volume in pores of diameter greater than 8 Å and containingless than about 0.5% by weight alkali metal components, calculated asthe oxides thereof, and (2) a dispersion of silica-alumina in a matrixconsisting essentially of alumina.
 13. A hydrocracking catalystcomposition comprising a first component selected from the groupconsisting of the oxides and sulfides of molybdenum and tungsten and asecond component selected from the group consisting of the oxides andsulfides of nickel and cobalt supported on an intimate admixturecomprising a crystalline aluminosilicate zeolite having crackingactivity and a dispersion of silica-alumina in a matrix consistingessentially of alumina.
 14. A catalyst composition as defined in claim11 or 13 wherein said zeolite has at least 50% of its pore volume inpores of diameter greater than 8 Å and contains one or more componentsselected from the group consisting of hydrogen ions, hydrogen ionprecursors, and multivalent metal-containing cations.
 15. A catalystcomposition as defined in claim 11, 12, or 13 wherein said zeolite ision exchanged to contain one or more rare earth metal ions.
 16. Acatalyst composition as defined in claim 11, 12 or 13 wherein saidsilica-alumina dispersed in said alumina contains between about 50 and90% by weight silica, and the dispersion of silica-alumina in saidalumina matrix comprises between 20 and 65% by weight silica-alumina.17. A catalyst composition as defined in claim 16 wherein said intimateadmixture comprises between 10 and 70% by weigh zeolite.
 18. A catalystcomposition as defined in claim 11, 12, or 13 wherein said zeolite isselected from the group consisting of Zeolite X, Zeolite Y, Zeolite L,and Zeolite Omega.
 19. A catalyst composition as defined in claim 11,12, or 13 wherein said zeolite is a modified hydrogen Y zeolite having aSiO₂ :Al₂ O₃ ratio between about 3.5 and 6, a surface area between about500 and 700 m² /gm, a unit cell size between about 24.25 and 24.35 Å, anion exchange capacity when in the sodium form less than 20% of that of asodium Y zeolite of comparable SiO₂ :Al₂ O₃ ratio, and a waterabsorption capacity, at 4.6 mm water vapor partial pressure and 25° C.,less than 8% by weight of the zeolite.
 20. A catalyst composition asdefined in claim 6, 7, 12, or 13 wherein said zeolite is hydrogen Yzeolite or a steam stabilized hydrogen Y zeolite.
 21. A catalystcomposition comprising one or more Group VIII metal components selectedfrom the group consisting of the oxides and sulfides of cobalt andnickel in a proportion between about 3 and 10 wt.%, calculated as NiOand CoO, one or more Group VIB metal components selected from the groupconsisting of the oxides and sulfides of molybdenum and tungsten in aproportion between about 10 and 30 wt.%, calculated as MoO₃ and WO₃,said Group VIII and VIB metal components being supported on an intimateadmixture of (1) a modified hydrogen Y zeolite having a SiO₂ :Al₂ O₃ratio between about 3.5:1 and 6:1, a surface area between about 500 and700 m² /gm, a unit cell size between about 24.25 and 24.35 Å, an ionexchange capacity when in the sodium form less than 20% of that of asodium Y zeolite of comparable SiO₂ :Al₂ O₃ ratio, and a waterabsorption capacity, at 4.6 mm water vapor partial pressure and 25° C.,less than 8% by weight of the zeolite and (2) an alumina matrix havingsilica-alumina heterogeneously dispersed therein.
 22. A catalystcomposition comprising one or more Group VIII metal components selectedfrom the group consisting of the oxides and sulfides of cobalt andnickel in a proportion between about 3 and 10 wt.%, calculated as NiOand CoO, and one or more Group VIB metal components selected from thegroup consisting of the oxides and sulfides of molybdenum and tungstenin a proportion between about 10 and 30 wt.%, calculated as MoO₃ andWO₃, said Group VIII and VIB metal components being supported on anintimate admixture of (1) a modified hydrogen Y zeolite having a unitcell size between about 24.25 and 24.35 Å and having a water absorptioncapacity, at 4.6 mm water vapor partial pressure and 25° C., less than8% by weight of the zeolite and (2) an alumina matrix havingsilica-alumina heterogeneously dispersed therein.
 23. A catalystcomposition comprising one or more Group VIII metal components selectedfrom the group consisting of the oxides and sulfides of cobalt andnickel in a proportion between about 3 and 10 wt.%, calculated as NiOand CoO, one or more Group VIB metal components selected from the groupconsisting of the oxides and sulfides of molybdenum and tungsten in aproportion between about 10 and 30 wt.%, calculated as MoO₃ and WO₃,said Group VIII and VIB metal components being supported on an intimateadmixture of (1) a modified hydrogen Y zeolite having substantialactivity for catalytically cracking hydrocarbons and having an unit cellsize between about 24.25 and 24.35 Å and (2) an alumina matrix havingsilica-alumina heterogeneously dispersed therein.
 24. A catalystcomposition comprising one or more Group VIII metal components selectedfrom the group consisting of the oxides and sulfides of cobalt andnickel in a proportion between about 3 and 10 wt.%, calculated as NiOand CoO, and one or more Group VIB metal components selected from thegroup consisting of the oxides and sulfides of molybdenum and tungstenin a proportion between about 10 and 30 wt.%, calculated as MoO₃ andWO₃, said Group VIII and VIB metal components being supported on anintimate admixture of (1) a modified hydrogen Y zeollite having a unitcell size between about 24.25 and 24.35 Å and a water absorptioncapacity, at 4.6 mm water vapor partial pressure and 25° C., less than8% by weight of the zeolite and (2) a heterogeneous dispersion ofsilica-alumina in an alumina matrix, said dispersion comprising betweenabout 20 and 65% by weight of silica-alumina, with 50 to 90% of saidsilica-alumina being silica.
 25. A catalyst composition comprising oneor more Group VIII metal components selected from the group consistingof the oxides and sulfides of cobalt and nickel in a proportion betweenabout 3 and 10 wt.%, calculated as NiO and CoO, one or more Group VIBmetal components selected from the group consisting of the oxides andsulfides of molybdenum and tungsten in a proportion between about 10 and30 wt.%, calculated as MoO₃ and WO₃, said Group VIII and VIB metalcomponents being supported on an intimate admixture of (1) a Y zeolitehaving substantial activity for catalytically cracking hydrocarbons,said Y zeolite having been ion-exchanged to contain one or morecomponents selected from the group consisting of hydrogen ions, hydrogenion precursors, and multivalent metal-containing cations and (2) analumina matrix having silica-alumina heterogeneously dispersed therein.26. A catalyst composition as defined in claim 6, 7, 11, 12, 13, or 25wheren said zeolite has been ion exchanged to contain a substantialproportion of hydrogen ions in the ion exchange sites.
 27. A catalystcomposition as defined in claim 6, 7, 11, 12, or 13 wherein said zeoliteis a modified hydrogen Y zeolite having a unit cell size between about24.25 and about 24.35 Å and a water absorption capacity, at 4.6 mm watervapor partial pressure and 25° C., less than 8% by weight of thezeolite.
 28. A catalyst composition as defined in claim 17 wherein saidzeolite is a modified hydrogen Y zeolite having a unit cell size betweenabout 24.25 and 24.35 Å and a water absorption capacity, at 4.6 mm watervapor partial pressure and 25° C., less than 8% by weight of thezeolite.
 29. A catalyst composition as defined in claim 6, 7, 21, 22,23, or 25 wherein said silica-alumina dispersed in said alumina containsbetween about 50 and 90% by weight silica, and the dispersion ofsilica-alumina in said alumina matrix comprises between 20 and 65% byweight silica-alumina, and said zeolite, having been ion exchanged tocontain a substantial proportion of hydrogen ions, comprises betweenabout 10 and 70% of said intimate admixture.
 30. A catalyst compositioncomprising a Group VIB or Group VIII hydrogenation component intimatelycomposited with a zeolite-containing support, said support having beenprepared by a method comprising the steps of:(1) calcining anammonium-exchanged zeolite Y containing between about 0.6 and 5 weightpercent socium, calculated as Na₂ O, at a temperature between about 600°and 1650° F. in contact with water vapor for a sufficient time tosubstantially reduce the unit cell size of said zeolite and bring it toa value between about 24.40 and 24.64 Å; (2) subjecting the calcinedzeolite to further ammonium ion exchange under conditions such that thesodium content of the zeolite is reduced below about 0.6 weight percent,calculated as Na₂ O; (3) calcining the zeolite obtained from step (2) incontact with sufficient water vapor and for a sufficient time such thatthe unit cell size of the zeolite is reduced to between about 24.25 and24.35 Å and the water absorption capacity of the zeolite at 4.6 mm watervapor partial pressure and 25° C. is less than 8% by weight of thezeolite; and (4) intimately admixing the zeolite obtained from step (3)with a dispersion of silica-alumina in a gamma alumina matrix, andcalcining the resulting admixture.
 31. A catalyst composition as definedin claim 30 wherein said catalyst comprises both a Group VIB and a GroupVIII hydrogenation component.
 32. A catalyst composition as defined inclaim 30 wherein said catalyst comprises a Group VIB metal oxide orsulfide and a Group VIII metal oxide or sulfide.
 33. A catalystcomposition as defined in claim 30, 31, or 32 wherein said zeolite atthe end of step (2) contains about 0.25 weight percent sodium,calculated as Na₂ 0, and at the end of step (3) has a water absorptioncapacity at 4.6 mm water vapor partial pressure and 25° C. of about 4.6%by weight of the zeolite.
 34. A catalyst composition as defined in claim33 wherein said dispersion consists essentially of silica-aluminacontaining between about 50 and 90% by weight silica dispersed in gammaalumina, the overall silica content of the dispersion being betweenabout 20 and 65% by weight silica-alumina.
 35. A catalyst composition asdefined in claim 30, 31, or 32 wherein said dispersion consistsessentially of silica-alumina containing between about 50 and 90% byweight silica dispersed in gamma alumina, the overall silica content ofthe dispersion being between about 20 and 65% by weight silica-alumina.36. A catalyst composition as defined in claim 35 wherein the intimateadmixture of zeolite and dispersion comprises between 10 and 70% byweight zeolite.
 37. A catalyst composition as defined in claim 36wherein said catalyst comprises a Group VIII metal component selectedfrom the group consisting of the oxides and sulfides of nickel andcobalt and one or more Group VIB metal components selected from thegroup consisting of the oxides and sulfides of molybdenum and tungsten.